College of Engineering Technology and Computer Science (Lab Report Sample)

Tennessee State University
College of Engineering Technology and Computer Science
Department of Civil and Engineering
CVEN 3121- Mechanics of material lab
Instructor name:
Lab 3: Tensile test of brittle and ductile metals(clock-house machine)
Student name:
Date:
Term:
ABSTRACT
Tensile refers to the capability of material to be stretched or drawn out. A brittle material refers to a hard but easy to break. Ductile material refers to those materials that can be deformed without loosing their toughness. During the experiment, the specimen was used to determine its tensile strength. In the start of the experiment the original length and thickness of the specimen was measured first so as to note the change in length and thickness after the experiment. The original length and thickness were found to be 3.75mm and 0.1421mm respectively.
INTRODUCTION
Tensile test of brittle and ductile materials is an experiment done on materials to determine their tensile strength, whether they can withstand the tensile force and their capability not to break easily. This experiment helps engineers to know which materials are best for specific purposes in construction and manufacturing. Different materials have different tensile strengths, the tensile strength of material will determine its use and the place of use. When the material breaks easily, it means that the material is not suitable for use in areas where tensile force will be high. If a material withstands the highest force, it means that the material can be safely used in high tensile force areas.
The objectives of the test are to investigate how the material specimen behave under tensile test. After performing the test the following will be determined;
* Percentage reduction in cross-sectional area
* Percentage elongation
* Ultimate tensile stress
* Young’s modulus
* Yield stress
THEORETICAL BACKGROUND
The properties of the specimen describe how the material will behave during the experiment process. The fracture toughness of materials varies according to the environment, loading rate, temperature, and its composition. The fracture toughness tends to stop the progression of fracture in the specimen. As the specimen is being pulled, its elongation and strength can be found out. Under the force type on the specimen, it can be easily determined how the specimen will behave in tension.
In the test, the specimen is put to a continuous increasing one directional tensile force while observations being made of elongation of the ductile specimen.
During the experiment, it is assumed that the material used is made of the same material under the same conditions.
MATERIALS AND APPARATUS
The materials used were;
* Vernier caliper
* Micrometer
* Clock-house tension machine
* Specimen (S)

PROCEDURE
1 Measure the specimen thickness with the micrometer and the length with the Vernier calipers
2 Behind the digital control unit, turn panel switch on then allow 15minutes for warm up
3 Measure the distance from the bottom jaw to the top of the bottom jaw
4 Place the specimen in the grip making sure that evenly place with the top jaw then release the lever. Leave the bottom grip open
5 On the control panel, push the 4th button and zero the reading using the fine adjustment, zero the peak load reading; pushing the top right button F2
6 On the clock house machine, reach down the knob (at the lower right front of the machine0 and pull out while moving the pushed in large black wheel back and forth until it locks
7 Release the button grip on the specimen
8 Before you start the test turn the feed controls on the control column to the desired feed rates, the dial is calibrated in MM/MIN.
9 Watch the reading on the control panel when the panel reading has been reached the yield point of the specimen has been reached.
10 Stop the machine on the control column.

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